The present disclosure relates to a driving device for driving a display device (such as a liquid crystal display (LCD), a plasma display panel (PDP), and digital light processing (DLP)), an LCD, and a driving method for driving a display device, and more particularly, to a driving device for driving a display device which displays an image by dividing a frame into a plurality of sub-frames using a digitized video signal as an input signal, an LCD, and a driving method for driving a display device.
A method for driving a liquid crystal display element used in an LCD is divided into an analog mode and a digital mode. The analog mode uses continuous analog voltage values applied to a pixel. The digital mode controls an effective voltage value using a binary voltage applied to a pixel of a liquid crystal, by varying a time width of the applied voltage depending on the luminance (color gradients) of an image.
Since the digital mode only applies information of “0” or “1” to a pixel, the digital mode is hardly influenced by external factors such as noise. A PDP and DLP are driven in the digital mode because of their display mechanisms.
The digital mode typically uses a sub-field method in order to generate halftone image's. The sub-field method is to display a halftone image using a visual integration effect of a viewer by preparing a predetermined number of sub-fields for one field period of a video signal, and appropriately selecting and displaying a sub-field depending on a gradient of the video signal displayed.
When an LCD employs the sub-field method, different digital values of “1” and “0” are indicated between adjacent pixels, and a lateral electric field is thus generated. The lateral electric field varies luminance between the pixels to cause deterioration of image quality Japanese Patent JP5834921 discloses a method of preventing deterioration of image quality caused by a lateral electric field, using a dithering circuit for gradient generation provided with frame rate control (FRC) at the end of the circuit so as to disperse the lateral electric field.
In association with recent demands for higher color gradients and higher contrast in image display devices, deterioration of image quality derived from a lateral electric field such as a Mach band illusion, which was hardly distinguished, tends to appear in a portion having a smooth and soft gradient, such as a ramp waveform and a sunset image.